Gene Expression Dynamics at the Neurovascular Unit During Early Regeneration After Cerebral Ischemia/Reperfusion Injury in Mice

Abstract

With increasing distribution of endovascular stroke therapies, transient middle cerebral artery occlusion (tMCAO) in mice now more than ever depicts a relevant patient population with recanalized M1 occlusion. In this case, the desired therapeutic effect of blood flow restauration is accompanied by breakdown of the blood-brain barrier (BBB) and secondary reperfusion injury. The aim of this study was to elucidate short and intermediate-term transcriptional patterns and the involved pathways covering the different cellular players at the neurovascular unit after transient large vessel occlusion. To achieve this, male C57Bl/6J mice were treated according to an intensive post-stroke care protocol after 60 min occlusion of the middle cerebral artery or sham surgery to allow a high survival rate. After 24 h or 7 days, RNA from microvessel fragments from the ipsilateral and the contralateral hemispheres was isolated and used for mRNA sequencing. Bioinformatic analyses allowed us to depict gene expression changes at two timepoints of neurovascular post-stroke injury and regeneration. We validated our dataset by quantitative real time PCR of BBB-associated targets with well-characterized post-stroke dynamics. Hence, this study provides a well-controlled transcriptome dataset of a translationally relevant mouse model 24 h and 7 days after stroke which might help to discover future therapeutic targets in cerebral ischemia/reperfusion injury.

HIF-1α is involved in blood–brain barrier dysfunction and paracellular migration of bacteria in pneumococcal meningitis

“…RNAseq analysis also indicated regulation of several pathways related to HIF-1α and VEGF such as NF-kap-paB, PDGFb and Ang/Tie2 signaling, as reported previously for RNAseq of brain microvessels from experimental stroke and glioma models [37,16]. In the current meningitis data set, we observe an increase in angiopoietin 2 (Ang-2) and a decrease in Tie2 as well as protein tyrosine phosphatase receptor type B (PTPRB; one of the top down-regulated genes).…”

“…6 d). Several genes known to be regulated by HIF-1α, such as angiopoietin2, Tie2, PTPRB that we reported previously for their role in BBB function in ischemic stroke and brain tumors [ 27 , 37 , 16 ], were dysregulated in the infected mice. Additionally, several BBB junctional genes such as occludin, claudin-5, and ZO-1 were found to be downregulated indicating a BBB breakdown (Fig.…”

“…We therefore analyzed gene regulation and signaling pathways in the BBB forming microvessels. Mice were intraperitoneally infected and brain microvessels were isolated for RNA sequencing and bioinformatic analyses as described previously [ 37 , 16 ] comparing them with healthy controls (Fig. 6 a).…”

“…As our data argue for an involvement of HIF-1α/VEGF from both in vitro infection experiments and from immunohistochemical analysis of meningitis samples, we elaborated HIF-1α/VEGF expression in vivo at the BBB. To this end, brain microvessels were freshly isolated post-infection and RNA sequencing was performed to obtain the transcriptional changes in an unbiased manner as we described previously [ 37 , 16 ]. Hematogenous infection of S. pneumoniae resulted in global transcriptional changes in the BBB microvessels demonstrated by the regulation of ~ 9000 genes out of ~ 21,000 genes.…”

Increased Immunosignals of Collagen IV and Fibronectin Indicate Ischemic Consequences for the Neurovascular Matrix Adhesion Zone in Various Animal Models and Human Stroke Tissue

“…Thus, the NVU consists of neurons, astrocytes, oligodendrocytes, microglia, the vasculature with its endothelium, and other cell types (Lo et al, 2003;del Zoppo, 2009del Zoppo, , 2010Iadecola, 2017). Over time, multiple ischemia-associated affections of NVU components were detected (e.g., Härtig et al, 2009;Michalski et al, 2010Michalski et al, , 2018Aleithe et al, 2019;Mages et al, 2019;Kestner et al, 2020). Furthermore, the blood-brain barrier (BBB) attracted interest as a highly dynamic part of the NVU (Yang et al, 2019).…”